Hyperparathyroidism

Definition

Hyperparathyroidism is a condition in which your body produces too much parathyroid hormone. This hormone helps maintain the proper levels of calcium and phosphorus in your body.

In hyperparathyroidism, the excess hormone results in an imbalance in calcium and phosphorus that can create a multitude of health problems. Hyperparathyroidism can lead to problems affecting your teeth, bones, nervous system, kidneys and muscles.

Treatment for hyperparathyroidism depends on several factors, including which type of hyperparathyroidism you have.

Symptoms

A majority of people with hyperparathyroidism have no signs or symptoms. In those who do, the symptoms frequently come on slowly and are usually subtle, such as a feeling of weakness or fatigue, or vague aches and pains. But more severe signs and symptoms of hyperparathyroidism can develop over time, including:

• Increased thirst and urination due to increased excretion of calcium in your urine (hypercalciuria)
• Kidney stones
• Abdominal pain
• Nausea, vomiting or loss of appetite
• Thinning bones (osteoporosis), leading to an increased risk of fractures
• Confusion or poor memory
• Muscle weakness or fatigue

Causes

The hormone parathyroid is manufactured by the small oval-shaped parathyroid glands in your neck, adjacent to your thyroid gland. Each of your four parathyroid glands is about the size of a pea.

The parathyroid glands maintain proper levels of both calcium and phosphorus in your body by turning the secretion of parathyroid hormone (PTH) off or on, much as a thermostat controls a heating system to maintain a constant air temperature. Vitamin D also is involved in regulating the amount of calcium in your blood.

Normally, this balancing act works well. When calcium levels in your blood fall too low, your parathyroid glands secrete enough PTH to restore the balance. PTH raises calcium levels by releasing calcium from your bones and increasing the amount of calcium absorbed from your small intestine. When blood calcium levels are too high, the parathyroid glands produce less PTH. But sometimes one or more of these glands produce too much hormone, leading to abnormally high levels of calcium (hypercalcemia) and low levels of phosphorus in your blood.

The mineral calcium is best known for its role in keeping your teeth and bones healthy. But calcium has other functions. It aids in the transmission of signals in nerve cells, and it's involved in muscle contraction. Phosphorus, another mineral, works in conjunction with calcium in these areas.

Types of hyperparathyroidism
Hyperparathyroidism can occur as one of two types — primary hyperparathyroidism or secondary hyperparathyroidism.

• Primary hyperparathyroidism. Most often, this type is caused by a benign growth (adenoma) on one of the parathyroid glands, although the disorder can also occur when two or more glands become enlarged (hyperplasia) and produce too much hormone. In rare cases, the cause of hyperparathyroidism may be cancer of one of the parathyroid glands.
• Secondary hyperparathyroidism. This less common type occurs when another medical condition causes the parathyroid glands to produce too much PTH in response to chronically low levels of circulating calcium. Kidney failure, malabsorption problems and rickets, a disease caused by severe vitamin D deficiency, are the main causes of this type of hyperparathyroidism.

Parathyroid glands

Parathyroid glands

The parathyroid glands, which lie behind the thyroid, help regulate calcium metabolism. Either a deficiency or an excess of parathyroid hormone can cause problems.

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Risk factors

Twice as many women as men develop primary hyperparathyroidism, and risk increases with age. Two out of every 1,000 women age 65 and older will develop this disease. Infants and adults with vitamin D deficiency are at greater risk of developing secondary hyperparathyroidism.

Also at increased risk are people with multiple endocrine neoplasia, type I — a rare inherited syndrome that affects the parathyroid glands as well as the pancreas and pituitary gland. Having familial hyperparathyroidism — hyperparathyroidism that runs in families — puts you at risk as well.

Tests and diagnosis

Because hyperparathyroidism often causes few if any symptoms, you may not know you have the disorder until your doctor notices high levels of calcium on routine blood tests or on tests that screen for other disorders. Yet other diseases and certain medications also can increase the amount of calcium in your blood, so you'll receive a diagnosis of hyperparathyroidism only if blood tests show high levels of both calcium and parathyroid hormone.

Once hyperparathyroidism is diagnosed, your doctor may recommend tests to check for complications of the disorder. These may include:

• Bone mineral density test (bone densitometry). This noninvasive test requires virtually no preparation on your part, yet it can quickly assess your risk of osteoporosis, a condition that causes weak, brittle bones that fracture easily. Although some drugstores offer simple bone density tests, the best screening test for osteoporosis is dual energy X-ray absorptiometry (DEXA). The procedure is quick, simple, and gives accurate results. It allows your doctor to measure the density of bones in your spine, hip and wrist — the areas most likely to be affected by osteoporosis — and to accurately follow changes in these bones over time. Other tests that can accurately measure bone density include ultrasound and quantitative computerized tomography (CT) scanning.
• Urine tests. A 24-hour collection of urine can provide information on your kidney function and the amount of calcium excreted in your urine.
• Imaging tests. To check for kidney stones, your doctor may recommend an abdominal X-ray.

To locate the abnormal parathyroid gland or glands, your doctor will likely use a sestamibi scan and a neck ultrasound. A sestamibi scan uses a radioisotope to help locate a tumor or abnormal parathyroid gland before surgery. For the scan, you're given a very small dose of a radioactive material that's absorbed only by the overactive parathyroid gland ¾ not healthy ones.

Sometimes you and your doctor may choose not to treat hyperparathyroidism right away, especially if your blood calcium is only mildly elevated. If so, your doctor will likely want to check your calcium levels and kidney function every six months and may also recommend an annual abdominal X-ray and a bone density test every one to two years. If the disease doesn't become worse over time, you may not need to have these tests as often.

Complications

Having too much parathyroid hormone can lead to several serious complications, including:

• Osteoporosis. Hyperparathyroidism poses a long-term threat to your bones — the more parathyroid hormone your parathyroid glands produce and release, the more calcium your bones lose. The result is weak, brittle bones that are prone to fractures.
• Kidney stones. Because your body tries to compensate for excess calcium by excreting more of the mineral in your urine, you're at increased risk of developing kidney stones, which could then lead to kidney damage.
• Peptic ulcers. High blood levels of calcium stimulate your stomach to produce more acid, making you more likely to develop peptic ulcers.
• High blood pressure. High calcium levels can put you at increased risk of high blood pressure (hypertension) and congestive heart failure.
• Neonatal hyperparathyroidism. Severe, untreated hyperparathyroidism in pregnant women may cause dangerously low levels of calcium in newborns.

Treatments and drugs

Treatments for hyperparathyroidism, which can range from watchful waiting to surgery, depend on several factors, including the type of hyperparathyroidism you have and whether you're experiencing any signs or symptoms.

Primary hyperparathyroidism
If you don't have symptoms and your kidneys and bones are healthy, you and your doctor may choose a wait-and-see approach. Sometimes this may be all you need, although your kidney function, bone health and calcium levels will need to be monitored on a regular basis, usually about twice a year.

If you have complications, or moderate to severe symptoms, or your calcium level is elevated even though you don't have symptoms, your doctor may recommend one of the following:

• Surgery. Until recently, surgery to remove one or more parathyroid glands (parathyroidectomy) was the only option for people with symptomatic hyperparathyroidism, and it's still the gold standard treatment. In cases where the problem is an adenoma, just the one gland is removed. If all four glands are enlarged, your surgeon will likely remove three of them and sometimes part of the fourth.

  Traditionally, the surgery involved a long incision, exploration on both sides of the neck and general anesthesia. But a newer technique, known as minimally invasive parathyroidectomy, may offer a safer and less invasive approach for some people. During the operation, the surgeon uses sestamibi scan results as a map to locate the abnormal gland or glands. In some cases, a probe that detects radioactivity, much as a Geiger counter does, is used to confirm the location.

  The entire operation can usually be performed through a small incision in your neck. The surgery can often be done under local rather than general anesthesia. If local anesthesia is used, you likely can go home a few hours after surgery. Still, all surgery poses some risks. In a small percentage of people who have parathyroid surgery, the nerves controlling the vocal cords may be damaged, and some people develop chronically low calcium levels, requiring treatment with calcium and vitamin D. In addition, although it's usually very effective, parathyroid surgery won't cure the problem in every case.

• Hormone replacement therapy. For women who have gone through menopause and have signs of osteoporosis but no other symptoms, estrogen therapy may be an alternative to surgery. But taking oral estrogen may increase your risk of certain cancers. Work with your doctor to evaluate the risks and benefits to help you decide what's best for you.
• Medications. The drug cinacalcet (Sensipar) has been approved to treat secondary hyperparathyroidism in people with kidney disease and parathyroid cancer. In clinical trials, it also appeared to effectively treat primary hyperparathyroidism.

Secondary hyperparathyroidism
In cases of secondary hyperparathyroidism, the first goal is to treat the underlying problem. Chronic kidney failure is the most common disease causing secondary hyperparathyroidism. Damaged kidneys can't convert vitamin D to the active form, so doctors use an active form of vitamin D to reduce the production of PTH. After many years, vitamin D treatment can lose its effectiveness in some people, and excessively high levels of both calcium and phosphorus may occur. The drug cinacalcet (Sensipar) can reduce PTH levels, which lowers the chance of this occurring.

Lifestyle and home remedies

If you and your doctor have chosen to monitor, rather than treat, your hyperparathyroidism, the following suggestions can help prevent complications:

• Drink plenty of fluids, especially water. Drinking lots of fluids can help prevent kidney stones from forming.
• Exercise. This is one of the best ways to build strong bones and slow bone loss. Try to combine strength training with weight-bearing exercises. Strength training builds muscles and bones in your arms and upper spine. Weight-bearing exercises — such as walking, jogging, running, stair climbing, skipping rope, skiing and impact-producing sports — mainly affect the bones in your legs, hips and lower spine. If you're new to exercise, start out slowly and build up gradually. Aim for at least 30 minutes of exercise on most days.
• Get adequate amounts of vitamin D. Before age 50, experts recommend at least 200 international units (IU) of vitamin D every day. After age 50, vitamin D intake should be increased to between 400 and 800 IU daily.
• Don't smoke. Smoking may increase bone loss as well as increase your risk of a number of serious health problems, including cancer. Talk to your doctor about the best ways to quit.
• Be alert for conditions that may increase your calcium levels. Certain conditions, such as a gastrointestinal illness with vomiting and diarrhea, can cause your blood-calcium levels to rise. Call your doctor if you develop any of these conditions.